Ferrocenyl-based unsymmetrical azines as multisignaling sensors for Hg2+, Cu2+ in aqueous environment

Abstract

Seven ferrocenyl-based unsymmetrical azines 3a–3f and 5a were synthesized under metal-free conditions in good yields. Ferrocene-based unsymmetrical azines 3f and 5a have shown to be excellent multichannel chemosensors for Hg2+ and Cu2+ ions in aqueous environment. The color of the solution containing chemosensor 3f changed from yellow to colorless, upon the addition of Hg2+ and Cu2+ ions. Quantification of the absorption titration analysis shows that the detection limit was 6.77×10−7M for 3f-Cu2+ and 7.19×10−7M for 3f-Hg2+, respectively. For 5a, the detection limit can reach 1.29×10−7M and 2.40×10−7M for Cu2+ and Hg2+, respectively. Moreover, 1-substituted ferrocene-based unsymmetrical azines 3a–3e with electron-rich, electron-neutral, and electron-deficient aryl groups have significant influence on the sensitivity.